Pregnancy Weight Gain Calculator
Calculate your recommended pregnancy weight-gain range using pre-pregnancy BMI, gestational age and whether you are pregnant with one baby or twins. Track your current pregnancy weight gain against established guideline ranges.
Calculate recommended pregnancy weight gain
Enter your pre-pregnancy height and weight, current weight, gestational age and pregnancy type. Use the weight you had immediately before pregnancy when possible.
Recommended weight gain for a singleton pregnancy
The National Academies/IOM recommendations use pre-pregnancy BMI to establish total gestational weight-gain ranges and average rates during the second and third trimesters.
| Pre-pregnancy BMI | Category | Total gain (kg) | Total gain (lb) | 2nd/3rd trimester rate (kg/week) | 2nd/3rd trimester rate (lb/week) |
|---|---|---|---|---|---|
| <18.5 | Underweight | 12.5–18.0 | 28–40 | 0.44–0.58 | 1.0–1.3 |
| 18.5–24.9 | Normal weight | 11.5–16.0 | 25–35 | 0.35–0.50 | 0.8–1.0 |
| 25.0–29.9 | Overweight | 7.0–11.5 | 15–25 | 0.23–0.33 | 0.5–0.7 |
| ≥30.0 | Obesity | 5.0–9.0 | 11–20 | 0.17–0.27 | 0.4–0.6 |
These are population-level recommendations. Your clinician may individualize the target based on fetal growth, maternal health, nutrition, fluid status, pregnancy complications and other factors.
Recommended weight gain for twin pregnancy
Twin pregnancy requires different total weight-gain targets because there are two fetuses and greater placental and maternal physiologic changes. The CDC presents the following IOM-based total ranges:
| Pre-pregnancy BMI | Category | Total gain (kg) | Total gain (lb) |
|---|---|---|---|
| <18.5 | Underweight | 22.7–28.1* | 50–62* |
| 18.5–24.9 | Normal weight | 16.8–24.5 | 37–54 |
| 25.0–29.9 | Overweight | 14.1–22.7 | 31–50 |
| ≥30.0 | Obesity | 11.3–19.1 | 25–42 |
* CDC notes that the underweight twin recommendation is an exception to the IOM recommendations and should be individualized. Triplet or higher-order pregnancies require individualized specialist guidance.
How weight gain changes across pregnancy
First trimester
The National Academies framework assumes approximately 0.5–2.0 kg (1.1–4.4 lb) of weight gain in the first trimester. Morning sickness, appetite changes and individual variation can make early-pregnancy gain quite different from person to person.
Second and third trimesters
The IOM recommendations provide average weekly rates that differ according to pre-pregnancy BMI. The calculator uses those rates to create a practical singleton reference trajectory.
Weight gain is not perfectly linear
Real pregnancy weight does not necessarily increase by the same amount every week. Short-term fluctuations can occur because of hydration, food intake, bowel contents and fluid changes.
Twins need individualized monitoring
Total twin-pregnancy recommendations are higher, but the appropriate trajectory should be interpreted by the maternity team in the context of fetal growth and maternal health.
Healthy pregnancy weight-gain habits
- Choose a varied diet containing vegetables, fruits, whole grains, pulses, dairy or suitable alternatives and protein-rich foods.
- Prioritize nutrient-dense foods rather than trying to "eat for two" throughout pregnancy.
- Stay hydrated and follow individualized nutrition advice when nausea, vomiting, diabetes or other conditions affect intake.
- For most healthy pregnancies, aim for at least 150 minutes of moderate-intensity aerobic activity per week unless your clinician advises otherwise.
- Keep routine antenatal appointments so maternal weight and fetal growth can be assessed together.
- Do not start a weight-loss diet or aggressive exercise program during pregnancy without professional guidance.
CDC guidance states that, in general, additional calorie needs are not increased during the first trimester, with approximately 340 additional calories per day during the second trimester and 450 additional calories per day during the third trimester. Individual energy needs vary, so these figures should not be treated as a personalized diet prescription.
When to contact your maternity care provider
Contact your obstetrician, midwife or maternity care team if you have concerns about your weight trend, particularly when there is rapid unexplained weight gain, persistent inability to maintain nutrition or fluids, significant swelling, severe headache, visual symptoms, high blood pressure, or any other pregnancy warning sign.
The calculator's "below," "within" or "above" result is not a diagnosis. Clinical assessment should consider the complete pregnancy rather than one weight measurement.
Pregnancy Weight Gain Calculator FAQs
How much weight should I gain during pregnancy?
For a singleton pregnancy, recommended total weight gain is based on pre-pregnancy BMI: 28–40 lb (12.5–18 kg) for underweight, 25–35 lb (11.5–16 kg) for normal weight, 15–25 lb (7–11.5 kg) for overweight, and 11–20 lb (5–9 kg) for obesity.
Does pre-pregnancy BMI affect pregnancy weight gain recommendations?
Yes. The National Academies/IOM recommendations use pre-pregnancy BMI to set different total and second/third trimester weight-gain ranges.
How much weight gain is recommended in the first trimester?
The National Academies framework assumes approximately 0.5–2 kg (1.1–4.4 lb) of gain in the first trimester. Individual patterns vary, and some people gain little or no weight early in pregnancy.
Is pregnancy weight gain different with twins?
Yes. Recommended total weight gain is higher for twin pregnancies. The CDC lists 50–62 lb for underweight, 37–54 lb for normal BMI, 31–50 lb for overweight and 25–42 lb for obesity. The underweight twin range should be individualized.
Does this calculator tell me exactly how much I should weigh each week?
No. The calculator provides a guideline-based reference range. Pregnancy weight gain is not perfectly linear, and clinical decisions should consider the overall trend, fetal growth, nutrition, edema, medical conditions and other pregnancy factors.
What if I am gaining more or less than the recommended range?
A single measurement does not establish a problem. Discuss the pattern with your obstetric or maternity care provider, especially if weight changes are rapid, persistent, accompanied by swelling or other symptoms, or associated with concerns about fetal growth or nutrition.
Can I intentionally lose weight during pregnancy?
Intentional weight-loss dieting during pregnancy should not be undertaken without individualized medical advice. People who begin pregnancy with overweight or obesity may have different weight-gain targets, but the appropriate plan should be discussed with their maternity care provider.
Medical information disclaimer
This calculator is an educational tool based primarily on the National Academies/IOM gestational weight-gain recommendations as presented by CDC guidance. It does not diagnose malnutrition, obesity, fetal growth problems, preeclampsia or any other medical condition. It does not replace antenatal assessment by a qualified obstetrician, midwife, registered dietitian or other maternity professional. Individual recommendations may differ from calculator ranges.